// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_PROFILER_NATIVE_STACK_SAMPLER_H_
#define BASE_PROFILER_NATIVE_STACK_SAMPLER_H_

#include <memory>

#include "base/base_export.h"
#include "base/macros.h"
#include "base/profiler/stack_sampling_profiler.h"
#include "base/threading/platform_thread.h"

namespace base {

class NativeStackSamplerTestDelegate;

// NativeStackSampler is an implementation detail of StackSamplingProfiler. It
// abstracts the native implementation required to record a stack sample for a
// given thread.
class NativeStackSampler {
public:
    virtual ~NativeStackSampler();

    // Creates a stack sampler that records samples for |thread_handle|. Returns
    // null if this platform does not support stack sampling.
    static std::unique_ptr<NativeStackSampler> Create(
        PlatformThreadId thread_id,
        NativeStackSamplerTestDelegate* test_delegate);

    // The following functions are all called on the SamplingThread (not the
    // thread being sampled).

    // Notifies the sampler that we're starting to record a new profile. Modules
    // shared across samples in the profile should be recorded in |modules|.
    virtual void ProfileRecordingStarting(
        std::vector<StackSamplingProfiler::Module>* modules)
        = 0;

    // Records a stack sample to |sample|.
    virtual void RecordStackSample(StackSamplingProfiler::Sample* sample) = 0;

    // Notifies the sampler that we've stopped recording the current
    // profile.
    virtual void ProfileRecordingStopped() = 0;

protected:
    NativeStackSampler();

private:
    DISALLOW_COPY_AND_ASSIGN(NativeStackSampler);
};

// NativeStackSamplerTestDelegate provides seams for test code to execute during
// stack collection.
class BASE_EXPORT NativeStackSamplerTestDelegate {
public:
    virtual ~NativeStackSamplerTestDelegate();

    // Called after copying the stack and resuming the target thread, but prior to
    // walking the stack. Invoked on the SamplingThread.
    virtual void OnPreStackWalk() = 0;

protected:
    NativeStackSamplerTestDelegate();

private:
    DISALLOW_COPY_AND_ASSIGN(NativeStackSamplerTestDelegate);
};

} // namespace base

#endif // BASE_PROFILER_NATIVE_STACK_SAMPLER_H_
